PLEA 2008 – 25 th Conference on Passive and Low Energy Architecture, Dublin, 22 nd to 24 th October 2008 286: Assessment of Bioclimatic Applications in Buildings and the Consequent Reduction in Water Consumption when Using Evaporative Cooling Systems Luis Carlos Herrera 1 *, Gabriel Gómez-Azpeitia 2 Facultad de Arquitectura, Universidad de Colima, Colima, México 1* moreguachi@gmail.com Facultad de Arquitectura, Universidad de Colima, Colima, México 2 Abstract Chihuahua is found in the north of Mexico. It has an extreme hot dry climate. The hot season lasts for approximately 5 months. The high temperatures and common inadequate thermal envelope of buildings, obliges the use evaporative cooling to obtain comfort. The high water consumption that evaporative cooling requires (6 to 452 l/h) has been surprisingly ignored by the Mexican authorities. During the summer, a water saving program is implemented and the water supply is rationed of 4 to 6 hours per day, which obliges the use of tanks and cisterns. However, an extremely high percentage of stored water is used for evaporative cooling and not for other basic human needs. The experiment consisted of applying different bioclimatic criteria in five houses with identical characteristics: insulating the evaporative cooling equipment, installing window shading devices, applying additional insulation to the roof, increasing exterior wall mass and ventilating the house at night, where a evaporative cooling equipment were employed. The results demonstrated that the evaporative cooling equipment consume 50% more water than estimated by the suppliers and that the bioclimatic strategies employed indicate a maximum water saving of 32.1% in these conditions, and an average saving of 20.4 -21.93%. Keywords: water savings, evaporative cooling, bioclimatic strategies 1. Introduction Chihuahua City Mexico is located at the latitude of 28ºN, longitude of 106ºW and at an altitude of 1423m above sea level. Its climate is considered to be extreme warm and dry, with high temperatures in summer and scarce rainfall with recurrent periods of drought. Table 1, Meteorological Data of Chihuahua (C.N.A., 2003). Bioclimatic Parameters Average Average Temperature 24.7° C Maximum Temperature 32.0° C Maximum Extreme Temperature 41.3° C Minimum Temperature 17.5° C Minimum Extreme Temperature 4.5° C Temperature Oscillation 14.5° C Average Relative Humidity 52.80% Minimum Relative Humidity. 16.30% Maximum Relative Humidity 89.10% Annual Rainfall 313.1 mm Wind Direction Northeast Wind velocity 2.6m/s The hot summer period lasts for 5 months with an average extreme maximum temperature of 32ºC, a diurnal oscillation temperature of 14.5ºC, an average minimum relative humidity of 14%. The annual rainfall is 313.1mm. (Refer to table 1) The high summer temperatures and common inadequate thermal design of buildings obliges the occupants to recur to the use cooling equipment such as evaporative air-conditioning to obtain comfort. Evaporative cooling systems require considerable electric energy and a significant constant clean water supply. The high energy consumption has caused socioeconomic tension which has captured the attention of Mexican authorities. Surprisingly, the high water consumption seems to have been ignored 2. The water consumption of an evaporative cooling system in an arid zone. The Company IMPCO estimates that evaporative cooling systems consume from 6 to 452 liters per hour according to its capacity of 3000fcm to 42000fcm respectively. On the other hand the Partnership for Research Housing when considering cities like Albuquerque, Cheyenne and Phoenix, in the south of the United States, claims that the average water consumption is 12.6 l/h, whereas in Arizona it was found that evaporative cooling systems required 16.67l/h (Karpiscak, 1994). In the City of Juarez, Chihuahua, a study analyzing 4000fcm found that the average water consumption was 72.71 l/h (Martinez, 2007). These results are similar to those published by